The present invention is to be understood in light of what has previously been done in the field. However, the following discussion is not an acknowledgement or admission that any of the material referred to was published, used or part of the common general knowledge in Australia as at the priority date of the application.
The use of nutritional supplements by humans, and even animals, to improve general health or to improve, for example, athletic performance, is known. Nutritional supplements are not intended to provide all the nutrients necessary for a complete diet, but instead are generally intended to complement the dietary intake such that it becomes more nutritionally complete. It is recognised that vitamins, minerals and other substances found in such supplements play important physiological roles and that a deficiency of certain vitamins, minerals and/or other components of supplements has been linked to development of certain diseases, a decrease in general health or lower performance in athletes.
Conversely, nutritional supplements are known to enhance a variety of physiological states, under various conditions. There are many targets for nutritional supplements, for example sick patients, convalescing patients, elderly persons and persons undergoing strenuous exercise regimes who wish to improve their performance and/or recovery from such exercise.
The nutritional requirements of bodybuilders and persons engaged in strenuous physical exercise are quite particular, whether to decrease body fat and increase lean muscle mass, and or to improve recovery from the strenuous exercise. Recovery includes the ability to overcome exercise-induced inflammation.
Inflammation is a localised response to injury or destruction of tissues. It is characterised in the acute form by pain, heat, redness, swelling, and loss of function. Accordingly, reduced muscle inflammation includes, but is not limited to a reduction in any one or more of the aforementioned symptoms in muscle. The inflammatory response antagonises muscle protein synthesis and contributes to much of the physical discomfort experienced by persons 1 to 2 days after engaging in strenuous exercise, including resistance exercise training (MacIntyre D L, et al., Sports Med. 1995; 20(1):24-40; MacIntyre D L, et al., Eur J Appl Physiol. 2001; 84(3):180-6). If the inflammation is severe, anti-inflammatory drugs such as corticosteroids may be prescribed. However, the use of such drugs can have deleterious side-effects and, in many cases, is prohibited for athletes in competition.
Weight-bearing or resistance training exercise elicits a wide-range of responses in the activated muscle. There are anabolic signalling pathways activated by the stretch and strain of muscles and by growth factors which may be synthesised locally or circulate in the blood stream.
Modulation of the expression of various genes is an essential process in regulating the sequence of cellular events needed to activate stem cells that are located within the muscle bed (satellite cells) (Anderson & Wozniak, Can J Physiol Pharmacol. 2004; 82(5):300-10) to rapidly proliferate, before maturing and ultimately fusing with existing muscle fibres or joining together to create new muscle fibres. Regulators of the activation of satellite cells include Syndecan-3 (a transmembrane heparin sulphate proteoglycan essential for satellite cell proliferation), and Pax-7 (a protein that is essential for satellite cell activation and necessary for muscle tissue repair) (Seale et al., Dev Biol. 2004; 275(2):287-300; Cornelison et al., Dev Biol. 2001; 239(1):79-94). Other genes involved in the exercise-induced muscle repair and inflammation process include the small molecular weight chemokines (CCL2 and CCL4) and the early response genes, jun-B and c-fos.
If a natural food product, such as a product derived from milk, could be obtained having beneficial effects on exercise recovery it would be a readily available and safe therapeutic supplement.
It is known in the prior art to produce a milk product from cows maintained in a specific hyperimmune state, created by administering periodic booster immunisations with sufficiently high doses of antigens, which can be used to treat various diseases including arthritis, dermatitis and neoplastic diseases (EP 0 064103 A1, Beck L R). Normal cow's milk however does not contain the specific ‘anti-inflammatory factor’ present in milk produced from the aforementioned hyper-immunised animals, although it is believed to contain low levels of other anti-inflammatory factors. A person of skill in the art would appreciate that production of the anti-inflammatory milk products according to EP 0 064103 A1 is very expensive and time consuming.
It is also known in the prior art to produce anti-inflammatory milk products comprising colostrum which is rich in immunoglobulins. Colostrum is the pre-milk produced immediately after birth before the breast secretions stabilize into milk. Prime colostrum from cows is obtained within the first six hours after calving and contains four times the protein found in milk from the same cow obtained 48 hours later. The immunoglobulin fraction of colostrum is loaded with antibodies, lactoferrin and immune enhancers. Lactoferrin is thought to enhance the anti-inflammatory effect of colostrum, and is the subject of U.S. Pat. No. 6,475,511 (Gohlke M B). Immunoglobulins are thought to act locally on immune function in the gut.
Protein supplementation has been used widely by persons undertaking resistance exercise training to promote muscle protein synthesis in order to repair muscle tissue and facilitate muscle growth. The nutritional supplementation may be provided in the form of a drink or food and includes protein powders to be mixed with liquid for use, nutritional bars and snack foods, tablets, capsules and other preparations. Suitable protein sources commercially available include hydrolysed milk proteins, caseinates, soy protein isolates and milk protein concentrates prepared from ultra-filtrated skim milk. Nutritional supplements which are based on other protein sources, such as whey protein, are also available and can be provided in the form of fruit juices, but are thought to be inadequate because they do not also provide a lipid source (WO 02/15720). In addition, it has been considered that some milk-derived proteins are not readily absorbed by the gut, or do not survive the harsh environment of the digestive system to have a therapeutic effect.
Whey growth factor extract (WGFE) is one such milk product which was thought to be susceptible to at least partial loss of biological activity once ingested due to fragmentation of molecules such as growth factors. Moreover, by virtue of the process for its isolation, WGFE contains only low levels of immunoglobulins which, as described above, are thought to be important anti-inflammatory factors.
Nevertheless, the capacity of whey protein supplementation to provide a benefit to persons engaged in resistance exercise training has been reported to provide a benefit. Whey protein isolate (WPI) and milk protein isolate (MPI), each having a different composition to whey growth factor extract, have been reported to be effective with bodybuilders in rapidly gaining lean muscle mass while reducing body fat. WPI is high in branched-chain amino acids and considered to be fast-acting, whereas MPI is mainly casein which is more slowly metabolised and is effective in promoting muscle growth. The use of WPI, or whey protein concentrate, in combination with the amino acids glutamine, leucine, isoleucine and valine to improve muscular fatigue in a rat model is the subject of WO 2004/049830 A1 (Tsuchita H et al.). The authors measured Tyrosine release from soleus muscle as the indicator of fatigue.
The present inventors have found that a composition comprising whey growth factor extract altered the expression of genes involved in exercise-induced muscle inflammation and was 40 fold more effective than colostrum at inhibiting LPS-induced production of the pro-inflammatory cytokine TNF-alpha in an in vitro model of inflammation (See FIG. 7 and Example 2). In a separate study conducted by the inventors, trained athletes administered whey growth factor extract reported a reduction in post-exercise soreness. Importantly, in terms of the invention, whey growth factor extract may be isolated from normal bulk milk products without a requirement to maintain cows in a hyperimmune state or to harvest colostrum which is in limited supply relative to other milk products.